Effect of foliar application of zinc, boron, copper andiron on flowering, fruiting and yield of strawberry (Fragaria× ananassa Duch.) cv. Chandler under semi-arid conditions

Introduction

Strawberry (Fragaria × ananassa Duch.) is an economically important small fruit crop valued for its attractive appearance, pleasant flavour, and nutritional and functional-food properties. The crop has gained considerable importance in commercial horticulture because of its high consumer demand and economic value. Successful strawberry production requires adequate vegetative growth followed by efficient flowering, fruit set, fruit development, and yield formation. As strawberry has a relatively shallow root system and is commonly cultivated under intensive production systems, adequate and balanced mineral nutrition is essential for maintaining healthy plant growth and achieving optimum fruit yield. Micronutrients, although required in relatively small quantities, play essential roles in various physiological and biochemical processes associated with plant growth and reproduction. Zinc is involved in enzyme activation, membrane function, and several metabolic processes, whereas boron plays an important role in cellwall development, reproductive growth, pollen germination, and pollen-tube development. Iron is essential for chlorophyll formation and electron-transfer processes, while copper participates in redox reactions and various enzyme systems. An adequate supply of these micronutrients is therefore important for maintaining normal physiological activity and reproductive development. Deficiency or imbalance of micronutrients may adversely affect flowering, fruit set, fruit development, and ultimately crop productivity. Foliar application is an effective approach for supplying nutrients directly to the aerial parts of plants and may provide rapid nutrient availability during critical stages of crop development. It can be particularly useful when nutrient availability in the soil or nutrient uptake through the root system is limited. Previous studies have reported beneficial effects of foliar application of micronutrients, particularly zinc, boron, and iron, on growth, flowering, fruiting, yield, and quality attributes of strawberry. Combined application of micronutrients has also been reported to improve fruit yield and quality in strawberry, including cv. Chandler.

However, the response of strawberry to micronutrient application can vary depending on cultivar, agro-climatic conditions, nutrient concentration, method and timing of application, and overall production system. Therefore, location-specific evaluation of suitable micronutrient combinations is important for developing efficient nutrient management practices. Under the semi-arid conditions of north-western Rajasthan, information on the response of strawberry cv. Chandler to foliar application of selected micronutrients and their combinations remains limited. Therefore, the present investigation was undertaken to evaluate the effects of selected micronutrients and their combinations on flowering, fruiting, and yield of strawberry (Fragaria × ananassa Duch.) cv. Chandler under the agro-climatic conditions of Hanumangarh district, Rajasthan.

Materials and methods

Experimental site

The experiment was conducted during 2025 at Nathwana, Sangaria, Hanumangarh, Rajasthan, India, under field conditions using strawberry (Fragaria × ananassa Duch.) cv. Chandler. The experimental site represents the semi-arid agro-climatic conditions of north-western Rajasthan.

Experimental design and layout

The experiment was laid out in a Randomized Block Design (RBD) comprising ten treatments and three replications, resulting in a total of 30 experimental plots. Each experimental plot measured 2.0 × 2.0 m. Strawberry plants were established at a spacing of 30 × 30 cm, accommodating 36 plants per plot. Three representative plants were randomly selected and tagged in each plot for recording observations throughout the experimental period.

Planting and crop management

Uniform runners of strawberry cv. Chandler were transplanted on 15 November 2025. The plants were established on raised beds covered with black polyethylene mulch. Drip irrigation was used for irrigation and water management. All other recommended cultural and cropmanagement practices were maintained uniformly across the treatments in accordance with the experimental protocol to minimize variation other than that arising from the treatments.

Treatments and their application

Ten treatments were evaluated in the experiment as follows:

The micronutrient treatments were applied as foliar sprays according to the experimental schedule. Repeated foliar applications were made at approximately 15-20-day intervals. The treatments were applied uniformly according to the prescribed concentrations and experimental protocol.

Observations recorded

Observations were recorded on the following flowering, fruiting and yield attributes:

The observations were recorded from the tagged representative plants of each experimental plot, and treatment-wise values were used for statistical analysis.

Statistical analysis

The experimental data were statistically analyzed using the analysis of variance (ANOVA) appropriate for a Randomized Block Design. The significance of treatment effects was tested using the F-test. Treatment means were compared using the Critical Difference (CD) at the 5% level of significance. The statistical analysis was carried out separately for each growth, flowering, fruiting and yield parameter.

Results

Effect on flowering and fruiting characteristics

Micronutrient treatments significantly influenced the reproductive behaviour of strawberry cv. Micronutrient application significantly affected the flowering and fruiting characteristics of strawberry cv. Chandler (Table 1). The days required for first flowering varied markedly among the treatments. The earliest flowering was recorded under T 10 (41.42 days), followed by T 7 (49.25 days) and T 5 (50.65 days), whereas the control (T 1 ) recorded the longest period to first flowering (87.26 days). Based on the reported treatment means, T 10 advanced the onset of flowering by 45.84 days compared with the control.

Treatment Treatment details

Control -RDF 100:60:60 kg N:P ha⁻¹ T 2

Azotobacter @ 5 kg ha⁻¹ T 3 PSB @ 5 kg ha⁻¹ T 4

Azospirillum @ 5 kg ha⁻¹ T 5

Copper sulphate @ 0.4% T 7

Ferrous sulphate @ 0.4% T 8

Zinc sulphate @ 0.2% + boric acid @ 0.2% T 10

Zinc sulphate @ 0.1% + boric acid @ 0.1% + copper sulphate @ 0.1% + ferrous sulphate @ 0.1%

The number of flowers plant⁻¹ was also highest under T 10 (24.30), followed by T 9 (18.66) and T 7 (18.29), while the lowest value was recorded under T 1 (13.78). Thus, T 10 produced 76.34% more flowers plant⁻¹ than the control. The treatment differences exceeded the corresponding critical difference at the 5% level for several treatment comparisons, indicating a significant treatment effect.

Fruit set was highest under T 10 (83.98%), followed by T 9 (77.38%) and T 5 (76.82%), whereas the minimum fruit set was recorded in T 1 (68.07% 2). The number of fruits plant⁻¹ ranged from 10.22 in the control (T 1 ) to 20.40 under the combined micronutrient treatment (T 10 ). Among the micronutrient treatments, T 10 recorded the highest number of fruits plant⁻¹ (20.40), followed by T 9 (14.41) and T 7 (13.98), whereas the minimum value was recorded under T 1 (10.22). The number of fruits plant⁻¹ under T 10 was approximately 99.6% higher than that recorded under the control. Individual fruit weight showed a similar treatment response. The maximum fruit weight was recorded under T 10 (16.52 g), followed by T 9 (13.96 g), T 7 (13.90 g) and T 5 (13.53 g), while the minimum value was observed under T 1 (10.10 g). Thus, fruit weight under T 10 was approximately 63.6% higher than that under the control. The observed treatment differences were greater than the reported CD (5%) in several comparisons, indicating substantial treatment effects on individual fruit weight.

Effect on number of fruits and fruit weight

Fruit yield plant⁻¹ varied considerably among treatments. T 10 recorded the highest yield (434.40 g plant⁻¹), followed by T 9 (357.27 g plant⁻¹), T 7 (305.33 g plant⁻¹) and T 5 (269.40 g plant⁻¹), whereas T 1 recorded the lowest yield (152.43 g plant⁻¹). On comparison with the control, T 10 increased fruit yield plant⁻¹ by approximately 185.1%. The difference between T 10 and T 1 (281.97 g plant⁻¹) was considerably greater than the reported CD (5%) of 13.43 g plant⁻¹. The estimated fruit yield on a hectare basis followed the same general trend. The highest yield was recorded under T 10 (10.26 t ha⁻¹), followed by T 9 (9.47 t ha⁻¹), T 7 (8.81 t ha⁻¹) and T 5 (8.39 t ha⁻¹), whereas the lowest yield was recorded under T 1 (3.89 t ha⁻¹). Relative to the control, T 10 represented an increase of approximately 163.8% in estimated fruit yield. Taken together, the combined application of Zn, B, Cu and Fe under T 10 was associated with higher fruit number, greater individual fruit weight and consequently higher fruit yield than the control and the other treatments evaluated in the experiment. The consistency of the response across these yield-related attributes suggests that the treatment effect was expressed through both fruit number and fruit size, which contributed to the higher fruit yield recorded under T 10 .

Discussion

The present study revealed substantial variation in the reproductive and yield performance of strawberry cv. Chandler in response to foliar micronutrient treatments. The combined treatment T 10 , comprising ZnSO₄ 0.1% + boric acid 0.1% + CuSO₄ 0.1% + FeSO₄ 0.1%, was associated with earlier flowering, greater flower production, higher fruit set and earlier fruit maturity.

Practical implications

The findings indicate that foliar micronutrient management can be considered as a potential component of nutrient management for strawberry cv. Chandler under semi-arid conditions. The treatment combination evaluated as T 10 showed favourable reproductive and yield responses in the present experiment. However, its broader commercial recommendation requires validation across seasons, locations and contrasting soil and production conditions. Optimization of spray concentration and application frequency is also necessary to ensure adequate nutrient supply without causing foliar or fruit injury.

Conclusion

The present study demonstrated that foliar micronutrient application influenced flowering, fruit set, fruit development and yield of strawberry cv. Chandler under the agro-climatic conditions of Hanumangarh, Rajasthan. Among the treatments evaluated, T 10 comprising ZnSO₄ 0.1% + boric acid 0.1% + CuSO₄ 0.1% + FeSO₄ 0.1% recorded the most favourable overall response, with earlier flowering and fruit maturity, greater flower and fruit production, higher fruit set and individual fruit weight, and consequently higher fruit yield. The improved performance may be attributed to the complementary physiological roles of Zn, B, Fe and Cu in reproductive development, pollen-related processes, enzyme activity and fruit development, although the present experimental design does not permit their individual or interactive effects to be separated. Therefore, the tested mi-cronutrient combination showed potential for improving strawberry productivity under the conditions of the present study. Further multiseason and multi-location studies are required to validate the consistency of the response and to establish an agronomically and economically appropriate foliar spray schedule

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